Otitis media, which is the most common disease in the pediatric population, is believed clinically one of to cause a deterioration of balance. Despite this prevalence of otitis media, its effect on balance function has not been systematically evaluated. The overall objectives of this proposal are to study vestibular and balance function and motor development in a cohort of 150 children ages 2 to 7 years, and determine the short- and long-term effects of otitis media with effusion on the balance and vestibular system. The experimental design includes yearly vestibular and balance evaluations and assessment of motor development of children when middle ear status is normal. Additionally, testing will be performed whenever an episode of otitis media with effusion develops as well as before and after tympanotomy tube insertion. Middle ear status will be assessed with pneumatic otoscopy, tympanometry, and audiometry. Vestibular testing will consist of ocular-motor screening, caloric testing, positional testing, rotational testing, moving platform posturography, and optic flow testing. Gross motor development also will be evaluated using the Peabody Developmental Motor Scale. This study will prospectively establish: 1) normative age-appropriate vestibulr and balance data and evaluate the maturation of the vestibular and balance system in a cohort of children with documented middle ear history since birth; 2) the effect of otitis media with effusion, including the effect of unilateral vs Bilateral effusion, and tympanotomy tube insertion on vestibular and balance function and motor function; and 3) which aspects of vestibular function are affected by otitis media and possible adaptive mechanisms.